Peel one jumbo white onion and cut into 1/2 slices. Separate into rings and put into a bowl of ice water. Set aside.
Set up your breading station. Divide the flour in half between two pie plates. Stir the cayenne pepper into one pan. Pour the buttermilk into a small bowl and mix in the hot sauce. Set this pan between the two flour pans.
Heat oil to 350 deg. Decide how many rings you can cook at one time. Remember not to crowd them.
Remove a few rings from the water, shake off and dredge in the seasoned self-rising flour until well dusted.
Dip into seasoned buttermilk until well covered and dredge again in the next pan of flour. Repeat process with next rings.
Drop your battered rings carefully into the hot oil. The buttermilk and self-rising flour should react by puffing up into a light crispy coating.
Flip when they are the color you want. Pull from the oil and drain well on a paper covered plate.
Serve them while they're hot! They go nicely with some sweet and spicey ketchup or dipping sauce of your choice.
If you want to make a batch for the rest of your table without the heat just omit the cayenne and hot sauce. Self-rising flour already has salt added but if you need more feel free to add away.